1. Field of the Invention
This present invention refers to a diaphragm core of aluminum in the form of a spider web structure used to obtain a wide variety of diaphragm shapes including a flat, concave, convex (dome), cone, combination flat/concave, combination flat/convex and combination flat/cone. However, it more particularly applies to a dome shaped loudspeaker diaphragm employing this present core to obtain said shape.
2. Prior Art
There exists, conventional planar type loudspeakers which embody a diaphragm core of honey comb structure made of aluminium foil. This design results in high strength and lightness as well as being able to surpress lower degree modes or partial vibrations so as to broaden the higher frequencies or eliminate peak dip frequency anomaly that occurs in cone shaped diaphragms. However, in these planar type conventional loudspeakers, partial vibration modes do occur contrary to repeated claims. This is due in part to weak regions of the core structure usually the trimmed edge portions. Also, mechanical distortions could arise due to a large diaphragm having a relatively large bobbin diameter hence a large coil, which cuts down on speed while generating said distortions. In some designs that employ a short bobbin with a spider attached in its middle, the maximum excursion distance could be drastically reduced due to early bottoming. Also, in trying to eliminate resonance and increase the diaphragm strength, some designs have attached to the diaphragm behind it, a support rib whose lower section is attached to the bobbin. This said support rib depending on material strength, weight and size could altogether be undesirable. Again in some conventional types of planar loudspeakers having the known honey comb structure in question, there is a tendency for the bobbin to come off its attachment with extended use due to the inadequate means of bonding the surfaces together with the bonding agent. However, the known planar type electro-acoustic transducer, U.S. Pat. No. 4,472,604 Sept. 18, 1984, Japan Pat. No. 0143625 11/79 Nakamura et. al. has an effective bonding technique which is also used in this present invention. However, it will be appreciated, the fact that due to the dome shape of this present invention a higher structural strength between the surfaces is obtained with this present invention for drivers of comparable size having the same maximum core height. Of course this is due to a lesser total diaphragm mass resulting from design. (See FIG. 15). Also, owing to the flat nature of their diaphragms resulting from the honey comb core, known planar type loudspeakers fail to achieve a great angle of dispersion of the radiated waves in relation to the degree or size of excursions. Again, in designs employing a coreless flat diaphragm made of fabric with an impregnated kitt, accurate pistonic motion is jeopardized. Conventional loudspeakers of the planar type affected by one or more of the aforementioned shortcomings include U.S. Pat. Nos. 4,322,583 3/82 Maeda, 4,122,314 10/78 Matsuda et al, 4,472,604 11/79 Nakamura et al, 3,937,905 Feb. 10, 1976, Germany Pat. No. 2236374 July 24, 1973 Manger.